JP5187120B2 - Image distribution device, terminal device, image distribution method, program, and recording medium - Google Patents

Description

  The present invention relates to an image distribution device, a terminal device, an image distribution method, a program, and a recording medium that perform processing for distributing an image code in response to a request transmitted from a client terminal.

  Conventionally, various image codes are distributed in response to a request from a client terminal from an image distribution apparatus such as an image distribution server installed in a public network such as the Internet that can be accessed by a general user. Forms of systems and services.

  Among such systems, particularly high-definition images and large-size images are stored, and in an image distribution device that distributes to client terminals, only a single image code data is used for distribution at a time. It is usually difficult to perform this process, and the distribution process is performed by dividing it into a plurality of image codes. The reason is that each of these images has a very large capacity, and a memory having a large capacity is required for processing, and it takes time to compress and decompress the data of the image code, which is not efficient. As an example of an image distribution apparatus, in a system that distributes data from a server to a client terminal via a network, if the data of the image code is single, the transfer amount during distribution becomes enormous, resulting in transfer errors and communication during transfer. This is because defects may occur.

  As a solution to such a problem, in an image code accumulation method such as the Flash Pix method, an image to be accumulated is divided into a plurality of images having a plurality of resolutions and different sizes and accumulated in a database. Yes. In addition, when displaying an image, the image code in the Flash Pix method is handled using a protocol using encryption referred to as IIP, and only the JPEG data related to the tile necessary for display is transmitted to the client terminal. This reduces the amount of data transferred.

  In recent years, as in the JPEG2000 system and the JPEG XR system, one image itself has a plurality of resolution hierarchies, and an encoding system capable of extracting only an image code of an arbitrary spatial region has been realized. Thus, the same functions and processes are realized without generating individual image files for each resolution and each spatial area as in the conventional Flash Pix method.

  Here, the encoding process of the image signal referred to as the normal transform encoding is executed in the following order. That is, the original signal of an image → color conversion (luminance / color difference conversion) → frequency conversion to subbands for each luminance / color difference → quantization of coefficients for each frequency region constituting the subband → entropy of coefficients after quantization Processing is performed in the order of encoding → bitstream generation, and the image signal is encoded.

  Among these series of processes, there are several methods for entropy coding of coefficients after quantization. Huffman coding, arithmetic coding, run-length coding, and predictive coding Any of these methods or a method combining these methods is available.

  In the predictive encoding process, a process using prediction of the image signal itself, a process using prediction of coefficients for each frequency domain, and the like are performed, and then a method such as Huffman encoding or run-length encoding. Combined with.

  Patent Document 1 below describes processing in which image data is handled by the Flash Pix method. The tile area including the window area and the extended tile are used as the image data area, and an appropriate layer is selected depending on the area size displayed in the window. If there is no data in the current image data area at the time of scrolling, the image data area is updated so that the insufficient tiles read in the scroll direction are maximized. Also, the image data area is updated so that the insufficient tiles to be read in the scroll direction are minimized.

  Further, in Patent Document 2, efficient overlay conversion is realized using a prefilter and a postfilter that are configured by a unit determinant component matrix. These pre-filters and post-filters are realized as a series of plane rotation transformations and unit deterministic plane scaling transformations, where the plane scaling transformations are implemented using plane shear deformation or lifting steps, and plane rotation and plane shear deformation are It has an implementation as a reversible / lossless operation, resulting in a reversible superposition operator.

  Patent Document 3 describes a system including a server and a client. The server stores a compressed code stream corresponding to image data, and the client is coupled to the server through a network environment. The client has a memory with an application and a stored data structure. This data structure shows the packet position of the compressed code stream in the server, and the compressed code stream data already buffered in the client. The client requests bytes of the compressed code stream from the server not yet stored in the memory, generates decoded image data requested by the user using the bytes of the compressed code stream requested from the server, and stores the image data. Generate a portion of the compressed codestream that is already stored in the memory needed to create it.

JP 2001-117554 A JP 2003-23630 A JP 2006-174487 A

  However, while the above predictive coding process can bias the image code data with a very simple algorithm, the image code data of the prediction source is required to obtain the value before the predictive coding. There is a drawback of becoming. Prediction coding is used even in an encoding method that can partially access an arbitrary resolution or spatial area of one image, and therefore, a prediction source image code that exists outside the resolution and spatial area to be accessed. In such a case, the amount of transfer data increases and the efficiency decreases.

  For example, when the image code stored in the image distribution apparatus on the image distribution side is accurately transmitted as it is, the client terminal on the reception side receives only an arbitrary partial image code for requesting distribution. However, it cannot be decoded correctly. For this reason, the image code of the other part including the part of the prediction source must also be transmitted together, and eventually the requested image can be decoded from the image code of the start part that affects the predictive coding process. All possible image codes must be delivered in succession.

  On the other hand, in order to reduce the amount of transferred data, when only the partial image code requested after being converted to a non-predicted image code that does not use predictive coding is distributed, decoding of the image code that is executed once, and In addition, there is a problem in that encoding processing for non-predicted image codes is added and costs are increased, and codes to be handled are increased by not using prediction.

  Here, in the JPEG XR system, predictive encoding processing is used. Predictive encoding in the JPEG XR system is not performed across tiles, which are the largest division units constituting an image, and therefore processing for extracting and restoring image codes for each tile is performed.

  However, even in the JPEG XR system, when tiling is not performed depending on the image code, that is, when the entire image is formed of only one tile, or when tiling is performed, When the size is very large, extraction of image codes for each tile and transmission / reception of image codes for each tile between the server and the client are inefficient. This is because even when the space area where the image is displayed is extremely small compared to the size of one tile, the image code transmitted from the image distribution device is greatly expanded from this space area to This is because tiles must be transmitted and the amount of transfer data increases.

  As described above, in the conventional technology, since the image code is extracted and distributed for each tile, which is the maximum division unit constituting the image by the JPEG XR method, the amount of transfer data increases and the efficiency is low. was there.

  The present invention has been made in view of such problems, and an image distribution device, a terminal device, an image distribution method, a program, and a recording capable of efficiently distributing image codes by reducing the amount of transfer data The purpose is to provide a medium.

  In order to solve the above problems, in the present invention, for example, an image distribution apparatus that distributes an image code of a spatial region designated by a client terminal among images encoded by a method such as a JPEG XR encoding method is received. The means receives, for example, image area designation information transmitted from a client terminal connected via a network, and reads out from the storage means an image code including a spatial area of the image designated by the image area designation information. Then, the extraction unit extracts a macro block for decoding the spatial area specified by the image area specifying information from the read image code, and performs a process of distributing the macro block to the client terminal.

  Further, the image distribution apparatus determines whether or not the predictive encoding process can be executed at the client terminal to be distributed, and if it is determined that the result is executable as a result, it is designated by the image area designation information from the image code. A prediction source macroblock for decoding the obtained spatial region using a predictive coding process is extracted. The image distribution device decodes the extracted prediction source macroblock, generates prediction source information, and performs processing for distributing these macroblocks and prediction source information to the client terminal.

  For this reason, the image distribution apparatus does not distribute an image encoded by, for example, the JPEG XR method for each tile that is the maximum division unit of data, but extracts and distributes macroblocks included in each tile. Therefore, the amount of transfer data can be reduced without distributing extra data included in each tile. It is possible to efficiently distribute the image code in the spatial region designated by the client terminal.

  According to the present invention, it is possible to provide an image distribution device, a terminal device, an image distribution method, a program, and a recording medium that can efficiently distribute image codes by reducing the amount of transfer data.

[First Embodiment]
Hereinafter, the present invention will be described with reference to embodiments. First, an outline of a JPEG XR encoding system, which is an example of an image encoding system used in an image distribution apparatus according to the present invention, will be described. FIG. 1 is an explanatory diagram showing a series of processes when decoding an image in the JPEG XR encoding method. In the JPEG XR encoding method, as shown in FIG. 1, after performing block overlap conversion processing selectively, through block frequency conversion, quantization, predictive encoding, etc., coefficient scanning and entropy encoding are performed. A display image is generated.

  Since the JPEG XR encoding method is a scalable image code like JPEG2000, it is possible to extract only a code representing a partial area having a certain resolution from the image code and decode the display image. . Further, in the JPEG XR encoding method, block conversion is used starting with tile data and macro blocks which are the maximum data division units, and predictive encoding processing is used.

  FIG. 2 is an explanatory diagram showing a spatial hierarchical structure composed of tile data, macroblocks, and the like in block conversion processing used in the JPEG XR encoding method. In the JPEG XR encoding method, for example, 4 × 4 pixels, which are the smallest unit in block conversion processing, are collected to form a “block”, and further, 4 × 4 “blocks” are collected to form a “macro”. A “Macroblock” is formed. Then, “tiles”, which are spatial areas such as rectangular shapes configured by arranging a plurality of “macroblocks”, are formed to obtain an image.

  The image encoding and decoding processes are performed individually for each tile data, and the predictive encoding process is not performed across a plurality of tile data.

  FIG. 3 is an explanatory diagram showing a plurality of frequency band hierarchies used when distributing image codes in the block conversion process used in the JPEG XR encoding method. As shown in FIG. 3, the JPEG XR encoding system has, for example, a three-stage frequency band hierarchy, and each of the DC band, LP (Low Pass) band, and HP (High Pass) band in order from the lowest frequency. It has a frequency band hierarchy.

  These frequency bands of the DC band, the LP band, and the HP band are generated as a result of executing the 4 × 4 PCT conversion process described later twice. The HP coefficient of the HP band is obtained by rearranging the coefficients after the first 4 × 4 PCT conversion process within the 4 × 4 pixel block.

  Next, the LP coefficient of the LP band is a coefficient at a predetermined position such as the upper left among the coefficients obtained by rearrangement in the first 4 × 4 PCT conversion process in each block (FIG. 3A, For example, in the case of FIG. 3 (a), 16 coefficients are collected from one macroblock from 4 × 4 blocks. These 16 collected coefficients are rearranged in the second 4 × 4 PCT conversion process.

  Finally, the DC coefficient is a coefficient at a predetermined position such as the upper left among the coefficients obtained by rearranging the 4 × 4 PCT conversion process for the second time in each block (FIGS. 3A and 3B). For example, in the case of FIG. 3A, 16 coefficients are collected from one macroblock from 4 × 4 blocks. A coefficient obtained by rearranging the collected 16 coefficients in the second 4 × 4 PCT conversion process is an LP coefficient.

  As a result, in the JPEG XR encoding method, three frequency bands, a DC band, an LP band, and an HP band, are generated and have three levels of resolution scalability. That is, in the JPEG XR encoding system, the same resolution as the original image is obtained with the HP coefficient, the resolution of 1/4 of the original image is obtained with the LP coefficient, and the resolution of 1/16 of the original image is obtained with the DC coefficient. For example, when the original image has a resolution of 480 × 480 pixels, an HP coefficient of 480 × 480, an LP coefficient of 120 × 120, and a DC coefficient of 30 × 30 are obtained.

(Flex Bits)
In the JPEG XR encoding method, an area referred to as Flex Bits for realizing scalability of each coefficient of HP coefficient, LP coefficient, and DC coefficient is formed in a part of the data area in addition to the frequency hierarchy. This Flex Bits corresponds to a Layer in the JPEG2000 encoding method.

  Each frequency band in each macroblock in the data area of the above JPEG XR encoding system and an area for forming Flex Bits are referred to as a subband signal.

(Definition of 2x2PCT and 4x4PCT)
Here, a PCT conversion formula used in the conversion process for obtaining the above-described DC coefficient, LP coefficient, and HP coefficient will be described. There are 2 × 2 versions and 4 × 4 versions of PCT conversion equations.
Hadamard conversion equation _{T H,}

とする。この場合、２×２ＰＣＴの変換式Ｔ_Ｈは、下記式（２）で与えられる、アダマール変換式Ｔ_Ｈのクロネッカー積で表される。

And In this case, conversion equation _{T H} of 2 × 2PCT is given by the following equation (2) is represented by the Kronecker product of a Hadamard conversion equation _{T H.}

更に、４×４ＰＣＴの変換処理は、上述の２×２ＰＣＴ変換式Ｔ_Ｈと、回転変換式Ｔ_Ｒで計算される３つの変換式により実現される。回転変換式Ｔ_Ｒを、下記式（３）、（４）で与える。

Furthermore, conversion of 4 × 4PCT includes a 2 × 2PCT conversion equation _{T H} described above is realized by three conversion formula calculated by the rotational transformation formula _{T R.} The rotation conversion equation _{T R,} the following equation (3), given by (4).

The 4 × 4 PCT conversion process includes three stages, and a 4 × 4 block that is a conversion range is defined by the following equation (5).

  The three stages described above are (1) a Hadamard transform stage, (2) a rotation stage, and (3) a coefficient rearrangement stage. The Hadamard transform stage and the rotation stage are expressed by the following formulas (6) and (7). Can be

図４は、上述した（３）の係数並び替えステージで、４×４ＰＣＴの変換処理後の係数を並び替えるために用いられる係数の配置を示す説明図である。上述のアダマール変換ステージおよび回転ステージを経て得られた係数を、図４に従って配置することで４×４ＰＣＴの変換処理が実現される。

FIG. 4 is an explanatory diagram showing the arrangement of coefficients used for rearranging the coefficients after the 4 × 4 PCT conversion process in the coefficient rearrangement stage (3) described above. 4 × 4 PCT conversion processing is realized by arranging the coefficients obtained through the Hadamard transform stage and the rotation stage described above according to FIG. 4.

(Conversion to reduce block noise)
Here, in the JPEG XR encoding method, as preparation processing for performing 2 × 2 PCT and 4 × 4 PCT conversion processing, POT conversion processing (POT = Photo Overlap Transform) across macroblocks for suppressing block noise. Option to do) is selectable. In the case of image encoding, when 4 × 4 PCT conversion processing is performed through POT conversion processing, it is necessary to perform inverse POT conversion processing in image decoding.

  FIG. 5 is an explanatory diagram showing a conversion range straddling between macro blocks in the POT conversion processing. In order to decode the original image, it is also necessary to refer to the image code for the macroblocks around the macroblock to be decoded. In this case, the end portion of the image area to be decoded is referred to. Note that there is a case in which such an end portion error is allowed, and it is possible to obtain a surrounding macroblock from a server or the like, and thus description thereof is omitted here.

(Bitstream structure)
The bitstream structure in the JPEG XR encoding system has a header including identification information about an image at the head, an index table indicating the position where the subband signal exists, and a structure in which the subband signal is arranged for each tile. Yes. There are two types of modes for the bitstream in the JPEG XR encoding method: Spatial mode and Frequency mode. These two types of modes are common in that subband signals are arranged for each tile. Yes. In the Spatial mode, all frequency band signals are arranged for each macroblock.

  FIG. 6 is an explanatory diagram showing the structure of the bit stream of these two modes in the JPEG XR encoding method. In the Spatial mode, for example, as shown in FIG. 6, all frequency band signals in the first macroblock are arranged, and subsequently, all frequency band signals in the second macroblock are arranged. The unit of frequency is divided for each macroblock unit and arranged outside.

  On the other hand, in the Frequency mode, in contrast to the Spatial mode, signals for all macroblocks are arranged for each frequency band.

  In the Frequency mode, for example, as shown in FIG. 6, the signals are divided into the DC band, LP band, HP band, and Flex Bits, and the signals of all the macroblocks are arranged for each frequency band. The signals of each macroblock in the band are arranged in the order of first, second, third,..., And then the signals of each macroblock in the LP coefficient are first, second, third, Are arranged in the order of..., And the unit of the macroblock is divided for each frequency band and arranged outside.

(Predictive coding)
In the JPEG XR encoding method, as shown in FIG. 1, a predictive encoding process is performed before entropy encoding of a subband signal. In the predictive coding process, subband signals for each frequency band of the DC band, LP band, and HP band are used separately, and different prediction modes are used for each frequency band. Note that, in any prediction mode, processing is performed for each tile data individually, and prediction coding processing is not performed across a plurality of tile data.

  FIG. 7 is an explanatory diagram illustrating a processing method of each prediction mode executed with a DC coefficient. First, in the predictive encoding process using DC coefficients, there are four types of prediction modes. As shown in FIG. 7, first, prediction is performed from the DC coefficient of the left macroblock, and second is DC of the upper macroblock. Prediction from coefficients, thirdly, prediction from numerical values obtained by adding the DC coefficients of the left and upper macroblocks and dividing by 2, and fourth, no prediction. Here, the fourth process without prediction is the same as the prediction from the zero value.

  Actually, in the predictive encoding process of DC coefficients, the predictive process from the numerical value obtained by adding the DC coefficients of the left and upper macroblocks and dividing by 2 is usually executed from the third method. If the difference in absolute value from the prediction source is less than or equal to a predetermined value, the first or second processing method is used.

  FIG. 8 is an explanatory diagram showing a processing method of each prediction mode executed with LP coefficients. In the predictive coding process with LP coefficients, there are three types of prediction modes, and as shown in FIG. 8, the first is prediction from the LP coefficient of the left macroblock, and the second is from the LP coefficient of the upper macroblock. And third, no prediction. Here, the predictive encoding process with LP coefficients is executed only between macroblocks using the same quantized numerical value shown in FIG. That is, the predictive encoding process using LP coefficients is not executed between macroblocks using different quantization values.

  Unlike the DC coefficient and the LP coefficient, the predictive encoding process using the HP coefficient is executed individually for each macroblock. In the predictive encoding process using HP coefficients, there are three types of prediction modes: first, prediction from the HP coefficient of the left macroblock, second, prediction from the HP coefficient of the upper macroblock, and third, prediction. None. FIG. 9 is an explanatory diagram showing a first processing method for predicting from the HP coefficient of the left macroblock among prediction modes executed with HP coefficients.

  In the predictive encoding process of the JPEG XR encoding method, since it is not performed across tiles, it is possible to individually decode an image within each tile. Since the predictive coding processing of DC coefficients and LP coefficients is executed across macroblocks, when image codes are exchanged for each macroblock, it is necessary to obtain the prediction source coefficients in order to decode the image. is there. On the other hand, since the HP coefficient is not performed across the macroblocks, it is possible to decode the image by individually performing predictive coding for each macroblock. However, in frequency inverse transform, an image cannot be restored unless there are correct values of DC coefficients and LP coefficients in the same macroblock.

(Coefficient scan)
In the JPEG XR encoding method, each subband signal is scanned in an adaptive order by coefficient scan processing. After the coefficient scan process, the non-zero coefficient value continues at the beginning, followed by the zero coefficient value, and the number of occurrences of the non-zero coefficient value is counted to adaptively correct the scanning order. The run-length encoding process that is subsequently performed is efficiently performed. FIG. 10 is an explanatory diagram showing an initial scan order in the coefficient scan process. In the coefficient scan process, as shown in FIG. 10, the initial horizontal scan order of LP coefficients and HP coefficients is (a), and the initial vertical scan order of HP coefficients is (b).

(Entropy coding)
JPEG XR encoding subband signal entropy encoding uses a combination of run-level encoding for zero coefficients and adaptive variable length processing among DC coefficient, LP coefficient, and HP coefficient values. . When all the coefficients of the subband signal are zero, the entropy coding is not performed and a process is performed with a flag indicating that all the coefficients are zero.

  Subsequently, the first embodiment of the present invention will be described, but the present invention is not limited to the embodiment. FIG. 16 is a schematic configuration diagram illustrating a hardware configuration of the server 100 which is an example of the image distribution apparatus according to the first embodiment. The server 100 has a function of distributing, for example, an image code of a spatial region designated by a client terminal 200 described later among images such as documents and photographs.

  The server 100 stores a receiving unit 105 that receives image area designation information for designating a space area in an image transmitted from the client terminal 200, and each piece of data including an image code that can be distributed to the client terminal 200. The image storage unit 110 includes an image code analysis unit 120 that reads out an image code including a spatial region designated by the image region designation information from the image code stored in the image storage unit 110 and performs an analysis process.

  Here, the image area designation information is information transmitted from the client terminal 200 to the server 100 via a network such as the Internet, for example. The image area designation information includes the range of the spatial area in the image code that the user requests to distribute among the image codes stored in the apparatus of the server 100 or in the image storage unit 110 that is connected so that the server 100 can be accessed. Contains information to specify. Examples of the information for designating the range of the space area include an image file name, the frame size of the space area for which distribution is requested, and offset coordinates for designating the space area.

  In the server 100, based on the image area designation information, an image code that is a macroblock extraction target is specified as described later, and a spatial area in the specified image code is specified to perform macroblock extraction processing. Done.

  In addition, when predictive coding processing can be performed by the client terminal 200, prediction processing is performed as processing necessary for predictive coding of an image after a macroblock including a spatial region is extracted from the image code. Original information is generated.

  The image code analysis unit 120 reads out an image code including the image code of the spatial region specified by the image region specification information from the image storage unit 110 and performs an analysis process. From the read image code, the image code is specified by the image region specification information. A process of extracting a macro block necessary for decoding the spatial region is performed.

  Further, the image code analysis unit 120 performs a process of determining whether or not the predictive coding process can be executed in the client terminal 200, and reads out from the image storage unit 110 when it is determined that the determination is possible. A process of extracting a prediction source macroblock for decoding the spatial area specified by the image area specifying information using the prediction encoding process is performed from the obtained image code. Then, the image code analysis unit 120 decodes the extracted prediction source macroblock, and prediction source information including subband coefficients for each frequency band of the DC band, the LP band, and the HP band included in the image code. Is generated.

  The server 100 includes a transmission unit 140 that transmits the macroblocks extracted by the analysis processing by the image code analysis unit 120 and the generated prediction source information to the client terminal 200 for distribution.

  The transmission unit 140 separates the macroblock extracted by the analysis processing by the image code analysis unit 120 for each frequency band of the DC band, the LP band, and the HP band, and distributes the macroblock to the client terminal 200. Further, when the image code analysis unit 120 determines that the predictive coding process can be performed, the transmission unit 140 receives the macroblock extracted by the image code analysis unit 120 and the generated prediction source information. Delivered to the client terminal 200. Here, the transmission unit 140 performs distribution using the following two methods.

  First, the first method is efficient when extracting from the code of the Spatial mode or reconfiguring, and one distribution data individually corresponds to one macroblock. The distribution data differs in data length depending on the distributed coefficient among the coefficients of each frequency band, and does not necessarily have the same data length as the macroblock code extracted by the image code analysis unit 120.

  FIG. 11 is an explanatory diagram showing the state of distribution data when all the coefficients for each frequency band related to one macroblock are transmitted up to the DC coefficient, LP coefficient, HP coefficient, and Flex Bits. FIG. 12 is an explanatory diagram showing the state of distribution data when a coefficient related to one macroblock is sent only up to an LP coefficient without sending an HP coefficient or less. Here, after sending up to LP coefficient once as distribution data, if you want to send only HP coefficient and Flex Bits for the same macroblock, send partial code consisting of HP and Flex Bits code to start HP coefficient What is necessary is just to add and send the position offset and length information.

  In the second method, one piece of distribution data individually corresponds to each coefficient for each frequency band that is divided into a plurality of macroblocks. The distribution data differs in data length depending on the distributed coefficient among the coefficients of each frequency band, and does not necessarily have the same data length as the macroblock code extracted by the image code analysis unit 120. Further, since each distribution data is individually distributed to each coefficient for each frequency band, it is necessary to attach a tile number, a macroblock number, ID information indicating a frequency band, and the like to each distribution data. In this method, distribution data is divided into coefficients for each frequency band and distributed in the minimum unit. Therefore, both the spatial mode and the frequency mode can be supported and the mode can be easily switched. FIG. 13 is an explanatory diagram showing a data structure of distribution data when the DC coefficient, LP coefficient, and HP coefficient individually included in one macroblock are individually sent for each frequency band.

  FIG. 14 is an explanatory diagram showing a data structure of distribution data distributed as a response to the image area designation information transmitted from the client terminal 200 by the server 100. As shown in FIG. 14, in this distribution data, as distribution data to be distributed by the above-mentioned first method, a macroblock message to which an image code header, an index table, a tile number, a macroblock number, and ID information are attached. Etc. are included.

  In addition, when the image code analysis unit 120 determines that the predictive encoding process can be executed, the distribution data includes a macroblock prediction value in addition to the above-described data.

  FIG. 15 is an explanatory diagram showing a data structure of a macroblock prediction value included in the distribution data shown in FIG. As shown in FIG. 15, the macroblock prediction value includes a DC coefficient value (DC prediction value) and an LP coefficient value (LP prediction value) used in the above-described predictive encoding process. If it is determined that the predictive coding process cannot be performed using the DC coefficient value, the DC coefficient value (DC predicted value) is “0”, while the predictive coding process is performed using the LP coefficient value. When it is determined as impossible, the LP coefficient value (LP predicted value) is “0”.

  FIG. 17 is a schematic configuration diagram illustrating a hardware configuration of a client terminal 200 that is a terminal device according to the present embodiment and receives an image code distributed from the server 100. The client terminal 200 includes a transmission unit 205 that transmits image area designation information to the server 100 via a network. The client terminal 200 can be configured as a personal computer, a PDA (Personal Data Assistant), a mobile phone, or the like.

  In addition, the client terminal 200 receives a macroblock distributed from the server 100 via the network and a reception unit 210 that receives the generated prediction source information, and image area designation information from the macroblock received by the reception unit 210 A process of decoding the spatial region specified in step S1 is performed, or the spatial region specified by the image region specification information from the macroblock and the prediction source information received by the receiving unit 210 is decoded using a prediction encoding process. A decoding unit 220 that performs processing is provided.

  The client terminal 200 includes an image display unit 230 that displays the space area decoded by the decoding unit 220 on a screen or the like as a display image.

  Next, a process in which the server 100 according to the first embodiment distributes the image code of the spatial region designated by the client terminal 200 will be described using the flowchart shown in FIG.

  First, the server 100 is set in a state where it is installed on the network and can distribute image codes. In step S1801, request information for requesting image distribution transmitted from the client terminal 200 by the receiving unit 105, and the request Image area designation information for designating the space area range and image resolution of the image code required by the information is received. For example, the following URI information including coordinates for designating a spatial region is used as the image region designation information.

  The URI information is information for designating a resolution when displaying an image and a spatial area of the entire image stored in the image storage unit 110. In the URI information, the spatial information is a rectangular spatial area. The coordinates of the upper left corner point (120, 0) and the coordinates of the lower right corner point (600, 480) are shown, indicating that an image is displayed with a pixel number of 480 × 480.

  The server 100 searches the image storage unit 110 by the image code analysis unit 120 in step S1802, and includes data relating to the image itself among the image codes including the spatial region specified by the image region specification information received in step S1801. Processing to read header information is performed. The header information includes the size of the entire image, the tile size, the definition of the color space, information indicating the bit stream start position in the image file, and the like.

  In step S1803, the server 100 performs processing for specifying the resolution of the image including the spatial region specified by the image region specifying information by the image code analysis unit 120. The server 100 uses the image code analysis unit 120 to analyze the image area designation information received in step S1801 and specify the resolution of the image code in the spatial area designated by the image area designation information. Then, the server 100 uses the image code analysis unit 120 to specify a subband coefficient corresponding to the specified resolution among the subband coefficients of each frequency band of the DC coefficient, the LP coefficient, and the HP coefficient.

  For example, when the server 100 receives the above-described URI information as the image area designation information, the image code analysis unit 120 analyzes the tail part of the image area designation information, and specifies information “& frame = 480, 480 ”, the resolution“ 480 × 480 ”of the image code of the spatial region delivered to the client terminal 200 is specified. Then, the server 100 uses the image code analysis unit 120 to specify a subband coefficient “HP coefficient” corresponding to the specified resolution among the subband coefficients of each frequency band.

  Further, for example, the server 100 analyzes the end part of the image area designation information by the image code analysis unit 120, refers to the information “& frame = 120, 120” for designating the resolution, and is distributed to the client terminal 200. The resolution “120 × 120” of the image code is specified. Then, the server 100 uses the image code analysis unit 120 to specify a subband coefficient “LP coefficient” corresponding to the specified resolution among the subband coefficients of each frequency band.

  Next, in step S1804, the server 100 performs a process of specifying a macroblock including the spatial region specified by the image region specifying information by the image code analysis unit 120. The server 100 uses the image code analysis unit 120 to analyze the image area designation information received in step S1801 and identify the spatial area designated by the image area designation information.

  Then, the server 100 searches the image storage unit 110 using the image code analysis unit 120, and identifies the tile number of each tile including the spatial region from the size and the coordinates of each tile including the identified spatial region. Also, among these identified tiles, the macroblock number including the spatial region is specified from the size of the macroblock including the spatial region and the respective coordinates.

  FIG. 19 is an explanatory diagram showing tiles and macroblocks including a spatial area designated by the image area designation information. As shown in FIG. 19, the server 100 searches the image storage unit 110 with the image code analysis unit 120 and, for example, tile numbers 1, 2, 4, 5,... Of each tile including a spatial region (Request Region). Is identified. Of these identified tiles, the macroblock numbers of the macroblocks (Response Region) including the spatial region are respectively tile numbers 1 to 7, 8, 11, 12,..., Tile numbers 2 to 9, 10 , 11, 12, 13... Are specified for each tile.

  In step S1805, the server 100 performs processing for extracting the image code of the macroblock including the spatial area specified by the image area specifying information by the image code analysis unit 120. The server 100 searches the image storage unit 110 using the image code analysis unit 120 and extracts a macro block that matches the macro block number identified in step S1804 from the image code including the spatial region specified by the image region specifying information. Perform the process. Here, the server 100 causes the image code analysis unit 120 to extract subband coefficient data corresponding to the resolution specified in step S1803 from the subband coefficients of each frequency band included in each macroblock.

  FIG. 20 is an explanatory diagram showing a state in which a macroblock including a spatial area designated by the image area designation information is extracted. For example, as shown in FIG. 20, the server 100 searches the image storage unit 110 using the image code analysis unit 120, and in step S1804, sets the macroblocks that match the macroblock number to tile numbers 1 to 7, 8, 11, ... And tile numbers 2 through 9, 10, 11, 12, 13... Are extracted for each tile.

  FIG. 21 is an explanatory diagram showing a state in which a macroblock is extracted when the image code has, for example, a Spatial mode bitstream structure. Here, as illustrated in FIG. 21, the server 100 uses the image code analysis unit 120 to select, for example, subband coefficients corresponding to the resolution specified in step S1804 among the subband coefficients of each frequency band included in each macroblock. Data of “HP coefficient” is extracted.

  In step S1806, the server 100 analyzes the image area designation information by the image code analysis unit 120, refers to the information regarding the client terminal 200 included in the image area designation information, and can perform predictive coding processing on the client terminal 200. The process which determines whether or not is performed.

  For example, when two data of the subband coefficients “DC coefficient” and “LP coefficient” are extracted from the subband coefficients of each frequency band included in each macroblock, the server 100 causes the image code analysis unit 120 to Thus, it is determined whether or not the predictive encoding process can be executed with any one of these two data. As a result of the determination, if it is determined that either one or two can be executed (Yes), the process of step S1807 is executed. If it is determined that both of the determination results are not executable (No), the process of step S1810 is executed.

  If it is determined that the execution is impossible (No), the server 100 distributes the image code of the macroblock extracted in step S1805 by the transmission unit 140 to the client terminal 200 in step S1810.

  If it is determined that the determination is possible (Yes), the server 100 predictively decodes the spatial region specified by the image region specifying information by the image code analysis unit 120 in step S1807 by the above-described predictive encoding process. Therefore, a process for specifying a prediction source macroblock necessary for the purpose is performed.

  FIG. 22 is an explanatory diagram illustrating a prediction source macroblock for predictively decoding a spatial region specified by image region specifying information. When the predictive encoding process predicts from the numerical value obtained by adding the DC coefficients of the left and upper macroblocks and dividing by 2, the server 100 uses the image code analysis unit 120 as shown in FIG. The image storage unit 110 is searched, and for example, the macroblocks at the left and upper positions of the macroblock extracted in step S1805 are specified as the prediction source macroblock.

  Next, in step S1808, the server 100 performs prediction decoding processing using the prediction source macroblock specified in step S1807 by the image code analysis unit 120, and performs processing to generate prediction source information.

  FIG. 23 is an explanatory diagram of prediction source information generated using a prediction source macroblock. When the predictive encoding process predicts from the DC coefficients and LP coefficients of the left and upper macroblocks, the server 100, for example, the macro of the spatial region specified by the image region specifying information as shown in FIG. Using the macro block numbers 6, 7, 9, 13, 17... Of the prediction source macro blocks necessary for accurately predictive decoding the block numbers 10, 11, 14, 15, 18, 19. Prediction decoding is performed, and the process of generating prediction source information by decoding the image codes of macroblock numbers 0 to 21 to the respective DC coefficient and LP coefficient regions.

  Then, the server 100 delivers the image code of the macroblock extracted in step S1805 by the transmission unit 140 in step S1809 and the prediction source information generated in step S1808 to the client terminal 200. Here, according to the request from the client terminal 200, the header information read in step S1802 is added and distributed as necessary.

  Next, a process in which the client terminal 200 in the first embodiment displays an image of the image code distributed from the server 100 will be described with reference to the flowchart shown in FIG. Here, a description will be given of a process in which the client terminal 200 can execute a predictive encoding process and displays an image by performing the predictive encoding process.

  First, the client terminal 200 transmits the image area designation information to the server 100 by the transmission unit 205, and then distributes the response from the server 100 as a response by using the transfer protocol such as http and tcp by the reception unit 210 in step S2401. Data including the image code and prediction source information of the macroblock that has been processed is received.

  In step S2402, the client terminal 200 analyzes the data content of the response received in step S2401 by the decoding unit 220, and extracts a macroblock message including macroblock header information and an image code, and prediction source information.

  In step S2403, the client terminal 200 performs processing for concatenating the subband coefficients included in the macroblock message extracted in step S2402 by the decoding unit 220 in raster order according to the bitstream structure.

  FIG. 25 is an explanatory diagram showing a state in which the subband signals included in the macroblock message are concatenated. The client terminal 200 converts each subband coefficient included in the macroblock message by the decoding unit 220, for example, in the raster order of DC coefficient, LP coefficient, HP coefficient, and FLEX BITS according to the bit stream structure of the Spatial mode as shown in FIG. Connect sequentially. Here, when the subband coefficients included in the macroblock message are only DC coefficients and LP coefficients, for example, flag information of coefficient value “0” is inserted in raster order as subband signals of HP coefficients and FLEX BITS. In addition, when the subband coefficients of the macroblock message not received in step S2401 are also connected, flag information with a coefficient value “0” is inserted into all the subband coefficients.

  In step S2404, the client terminal 200 entropy-decodes the subband signals for each macroblock connected in step S2403 by the decoding unit 220 in accordance with the JPEG XR encoding method, and acquires the subband coefficients of the prediction source macroblock.

  Next, in step S2405, the client terminal 200 performs a process of adding the macro blocks into which the flag information having the coefficient value “0” is inserted among the prediction source macro blocks by the decoding unit 220. Among the prediction source macroblocks entropy-decoded in step S2404 by the decoding unit 220, the client terminal 200 performs the same macroblock as the prediction source macroblock in which the flag information of the coefficient value “0” is inserted as described above. The macro block message extracted in S2402 is extracted, added as a prediction source macro block, and acquired.

  In step S2406, the client terminal 200 performs predictive decoding processing on each prediction source macroblock acquired in steps S2404 and S2405 by the decoding unit 220, and sets the image code of the macroblock in the spatial region specified by the image region specifying information. Perform the acquisition process.

  The client terminal 200 refers to the information related to the conversion process from the header information extracted in step S2402 with respect to the image code of the macroblock in the spatial region acquired in step S2406 by the decoding unit 220 in step S2407, and the above-mentioned Hadamard conversion stage. Inverse conversion processing is performed that is the reverse of the PCT / POT conversion processing in each of the rotation stage and the coefficient rearrangement stage.

  The client terminal 200 performs a decoding process, such as an inverse color conversion process, on the image code of the spatial region macroblock subjected to the inverse conversion process in step S2406 by the image display unit 230 in step S2407, and converts the display image into a display image. Generate and display on the screen.

  As described above, the server 100, which is the image distribution apparatus according to the first embodiment, searches the image storage unit 110 using the image code analysis unit 120, and includes tiles that include the spatial region specified by the image region specification information. A number is specified, and a macroblock including a spatial region is specified and extracted from each of the specified tiles, and distributed to the client terminal 200. On the other hand, when it is determined as a result of determining whether or not the predictive coding process can be executed by the client terminal 200, the server 100 determines a prediction source macroblock necessary for predictive decoding of the spatial region. It identifies and generates prediction source information and distributes it to the client terminal 200.

  For this reason, the server 100 includes an image encoded by, for example, the JPEG XR method, not in each tile that is the maximum data division unit, but in each tile that includes the spatial area among the tiles that include the spatial area. Therefore, it is possible to reduce the distribution of areas other than the space area, which is extra data of each tile, and to reduce the amount of transfer data. It is possible to efficiently distribute the image code in the spatial region designated by the client terminal.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. In the second embodiment, in step S1807 described above, the server 100 executes the process of specifying the prediction source macroblock by the image code analysis unit 120 as follows.

  FIG. 26 is an explanatory diagram illustrating a range of image codes of macroblocks that the server 100 distributes to the client terminal 200 by the transmission unit 140 in the second embodiment. In the first embodiment, as shown in FIG. 22 in the above-described step S1807, the spatial area specified by the image area specifying information and the macroblocks on the left and above the spatial area are specified as the prediction source macroblocks. However, in the second embodiment, as shown in FIG. 26, the server 100 identifies macroblocks within the spatial domain as the prediction source macroblock, and the macroblocks outside the spatial domain are assigned to the client terminal 200. It is not delivered.

  FIG. 27 is an explanatory diagram illustrating prediction source macroblocks identified by the server 100 in the second embodiment. In the second embodiment, the server 100 identifies macroblocks in the spatial domain as prediction source macroblocks, and predictive encoding processing predicts from the DC coefficients and LP coefficients of the left and upper macroblocks. In this case, as shown in FIG. 27, among these specified prediction source macroblocks, for example, tile number 1 to macroblock numbers 10, 11, 14, 18, 22, and tile number 2 to macroblocks at the upper and left ends. Prediction decoding of subband coefficients is repeatedly performed sequentially using each prediction source macroblock of numbers 8, 9, 10, 11, 12, 16, and 20, and prediction is performed by decoding up to each DC coefficient and LP coefficient region. Process to generate original information.

  The server 100 delivers to the client terminal 200 the prediction source information generated by the transmission unit 140 and the image code of the macroblock extracted in step S1805 described above.

  For this reason, the server 100 does not distribute an area other than the space area, which is extra data of each tile, and the amount of transfer data can be further reduced. It is possible to efficiently distribute the image code in the spatial region designated by the client terminal.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to the drawings. In the third embodiment, the server 100 replaces each DC coefficient or LP coefficient included in the prediction source information generated in the second embodiment with the coefficient of each macroblock, and again the macro within the range of the spatial region. Re-entropy code the sub-band coefficients of the entire block.

  Then, the server 100 distributes to the client terminal 200 the image code generated as a result of the re-entropy coding by the transmission unit 140 and the image code of the macroblock extracted in step S1805 described above.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to the drawings. In the fourth embodiment, the server 100 extracts the image code of the macro block including the spatial area specified by the image area specifying information by the image code analysis unit 120 in step S1805 described above, and then extracts each of these extracted macros. Prediction decoding is sequentially performed using blocks, and processing for generating prediction source information by decoding up to each DC coefficient and LP coefficient region is performed.

  Then, the server 100 distributes the prediction source information generated by the transmission unit 140 and the image code of the macroblock extracted in step S1805 described above to the client terminal 200.

  FIG. 28 is an explanatory diagram showing a macroblock including a spatial area designated by the image area designation information and a prediction source macroblock. When the resolution specified in step S1803 is the maximum value and the predictive coding process predicts from the DC coefficients and LP coefficients of the left and upper macroblocks and predicts from the HP coefficients of the left macroblock, The server 100 uses the image code analysis unit 120 to extract all the data from the DC coefficient to the Flex Bits, as subband coefficients of each frequency band included in each macroblock within the range of the spatial region (Response Region).

  In addition, the server 100 sequentially performs predictive decoding on each of the extracted data, and extracts each macroblock (Predicted Series Region) on the left and top of the spatial area necessary for decoding as a prediction source macroblock. I do. Note that since the prediction encoding process in the JPEG XR system is performed only for each DC coefficient and LP coefficient, only DC coefficient and LP coefficient data may be extracted for the prediction source macroblock. .

  FIG. 29 is an explanatory diagram illustrating another example of a macroblock including a spatial region designated by image region designation information and a prediction source macroblock. When the resolution specified in step S1803 is the maximum value and the predictive coding process predicts from each DC coefficient of the left macroblock, the server 100 causes the image code analysis unit 120 to use a resolution within the range of the spatial domain. All the data from the DC coefficient to the Flex Bits are extracted from the subband coefficients of each frequency band included in each macroblock.

  Further, the server 100 sequentially performs predictive decoding on each of the extracted data, and performs processing for extracting only DC coefficient data using each macroblock on the left side of the spatial region necessary for decoding as a prediction source macroblock. Do.

  For this reason, since the server 100 extracts only the subband coefficients necessary for the predictive coding process for the regions other than the spatial region, it is less likely that the redundant data of each tile is distributed. Also in the embodiment, the amount of transfer data can be reduced. It is possible to efficiently distribute the image code in the spatial region designated by the client terminal.

[Other Embodiments]
In the above-described embodiment, the image code including the spatial region designated by the image region designation information is distributed from the server 100 to the client terminal 200. However, the present invention is not limited to this, and the client terminal 200 has the same configuration as the server 100. May be. In this case, the client terminal 200 executes a series of processes in the above-described embodiments in the client terminal 200 using, for example, image area designation information input by a user operation, and the image display unit 230 performs image processing. Display.

  The functions of the present invention are described in legacy programming languages such as C, C ++, Java (registered trademark), Java (registered trademark) Applet, JavaScript (registered trademark) Script, Perl, and Ruby, and object-oriented programming languages. It can be realized by a program executable by the apparatus, and can be stored in a device-readable recording medium and distributed.

  The present invention has been described with the first to fourth embodiments shown in FIGS. 1 to 29, but the present invention is not limited to this. Other embodiments, additions, modifications, deletions, and the like can be changed without departing from the scope of the present invention, and any aspect is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited. It is what

It is explanatory drawing which shows a series of processes for decoding the image by the JPEG XR encoding system of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the spatial hierarchical structure of the image code used with the JPEG XR encoding system of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the frequency band hierarchy of the image code used with the JPEG XR encoding system of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows arrangement | positioning of the coefficient after the conversion process of 4x4 PCT of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the conversion range straddling between macroblocks in the conversion processing of POT of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the structure of the bit stream by the JPEG XR encoding system of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the processing method of each prediction mode performed with the DC coefficient of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the processing method of each prediction mode performed with the LP coefficient of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the processing method of the prediction mode performed with the HP coefficient of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the initial scanning order in the coefficient scanning process of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the mode of the delivery data in the case of sending the coefficient for every frequency band regarding the macroblock of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the mode of the delivery data in the case of sending the subband coefficient contained in the macroblock of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the mode of the delivery data in the case of sending the subband coefficient contained in the macroblock of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the mode of the delivery data in the case of sending the subband coefficient contained in the macroblock of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the mode of the delivery data delivered as a response of the image delivery apparatus in 1st Embodiment. It is a schematic block diagram which shows the hardware constitutions of the image delivery apparatus in 1st Embodiment. It is a schematic block diagram which shows the hardware constitutions of the client terminal of the image delivery apparatus in 1st Embodiment. It is a flowchart which shows the process which delivers the image code | symbol of the space area designated by the client terminal of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the tile and macroblock containing the space area | region designated with the image area | region designation | designated information of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows a mode that the macroblock containing the space area | region designated with the image area | region designation | designated information of the image delivery apparatus in 1st Embodiment was extracted. It is explanatory drawing which shows a mode that the macroblock was extracted from the bit stream structure of Spatial mode of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the prediction origin macroblock for carrying out the prediction decoding of the space area | region designated with the image area | region designation | designated information of the image delivery apparatus in 1st Embodiment. It is explanatory drawing which shows the prediction origin information produced | generated using the prediction origin macroblock of the image delivery apparatus in 1st Embodiment. It is a flowchart which shows the process in which the client terminal of the image delivery apparatus in 1st Embodiment displays the image code delivered from the image delivery apparatus. It is explanatory drawing which shows a mode that each subband signal contained in the macroblock message of the image delivery apparatus in 1st Embodiment was connected. It is explanatory drawing which shows the range of the image code of the macroblock delivered to the client terminal of the image delivery apparatus in 2nd Embodiment. It is explanatory drawing which shows the prediction origin macroblock of the image delivery apparatus in 2nd Embodiment. It is explanatory drawing which shows the macroblock containing the spatial area | region designated with the image area | region designation | designated information of the image delivery apparatus in 4th Embodiment, and a prediction origin macroblock. It is explanatory drawing which shows the other example of the macroblock containing the space area | region designated with the image area | region designation | designated information of the image delivery apparatus in 4th Embodiment, and a prediction origin macroblock.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Server, 105 ... Reception part, 110 ... Image storage part, 120 ... Image code analysis part, 130 ... Prediction decoding part, 140 ... Transmission part, 200 ... Client terminal, 205 ... Transmission part, 210 ... Reception part, 220 ... Decoding unit, 230 ... image display unit

Claims (10)

Among images, an image distribution device that distributes an image code of a spatial region designated by a client terminal via a network, wherein the image distribution device includes:
Storage means for storing images that can be distributed to the client terminal;
Receiving means for receiving image area designation information for designating a spatial area of the image transmitted from the client terminal;
A reading means for reading out an image code including a spatial area designated by the image area designation information received by the receiving means from the image stored in the storage means;
Extraction means for extracting a macroblock for decoding the spatial area specified by the image area specification information from the image code read by the reading means;
Distribution means for distributing the macroblock extracted by the extraction means to the client terminal ;
A determination unit that determines whether or not the process of predictive encoding is executable in the client terminal;
When it is determined that the determination unit can execute, the spatial region specified by the image region specification information is decoded from the image code read by the reading unit using the predictive encoding process. Second extraction means for extracting a prediction source macroblock for
Decoding means for generating prediction source information by decoding the prediction source macroblock extracted by the second extraction means;
An image distribution apparatus comprising: a macroblock extracted by the extraction unit; and a second distribution unit that distributes prediction source information to the client terminal by the generation unit . The image distribution apparatus according to claim 1, wherein the macroblock extracted by the extraction unit includes subband coefficients for each frequency band of a plurality of layers. The distribution unit distributes the macroblock extracted by the extraction unit to the client terminal via a network as a bit stream structure in which subband coefficients for all frequency bands are arranged for each macroblock unit. Item 3. The image distribution device according to Item 2 . The distribution unit distributes the macroblock extracted by the extraction unit to the client terminal via the network as a bit stream structure in which subband coefficients included in the macroblock are arranged for each of the frequency bands of the plurality of layers. The image delivery apparatus according to claim 2 . Wherein the generating means predicted based information generated by, contains sub-band coefficients of each frequency band of the plurality of layers, image delivery apparatus according to any one of claims 1-4. A terminal device that acquires an image code of a designated spatial region among images,
The terminal device
Storage means for storing the image;
A reading means for reading out an image code including a spatial area designated by image area designation information for designating a spatial area of the image from the image stored in the storage means;
Determination means for determining whether or not the process of predictive encoding is executable;
When it is determined that the determination unit can execute, the spatial region specified by the image region specification information is decoded from the image code read by the reading unit using the predictive encoding process. Macroblock extraction means for extracting a prediction source macroblock for
Generating means for decoding the prediction source macroblock extracted by the macroblock extraction means to generate prediction source information;
Means for obtaining prediction source information by the extracted macroblock and the generation means;
A terminal device. The extracted macroblock includes subband coefficients for each frequency band of a plurality of layers.
The terminal device according to claim 6 . An image distribution method executed by an image distribution apparatus, wherein the image distribution method includes:
Storing in the storage means an image that can be distributed to the client terminal;
Receiving image area designation information for designating a spatial area of the image transmitted from the client terminal;
Reading out an image code including a spatial region designated by the received image region designation information from the image stored in the storage unit;
Extracting a macroblock for decoding a spatial region designated by the image region designation information from the read image code;
Delivering the extracted macroblock to the client terminal ;
Determining whether or not predictive encoding processing can be executed at the client terminal;
When it is determined that the predictive encoding process is executable, the spatial region specified by the image region specifying information is decoded from the read image code using the predictive encoding process. A second extraction step of extracting a prediction source macroblock for
Decoding the prediction source macroblock extracted by the second extraction step to generate prediction source information;
A second distribution step of distributing the extracted macroblock and the generated prediction source information to the client terminal . A program executed by an image distribution device, the program being executed by the image distribution device,
Storage means for storing images that can be distributed to the client terminal;
Receiving means for receiving image area designation information for designating a spatial area of the image transmitted from the client terminal;
A reading means for reading out an image code including a spatial area designated by the image area designation information received by the receiving means from the image stored in the storage means;
Extraction means for extracting a macroblock for decoding the spatial area specified by the image area specification information from the image code read by the reading means;
Distribution means for distributing the macroblock extracted by the extraction means to the client terminal ;
A determination unit that determines whether or not the process of predictive encoding is executable in the client terminal;
When it is determined that the determination unit can execute, the spatial region specified by the image region specification information is decoded from the image code read by the reading unit using the predictive encoding process. Second extraction means for extracting a prediction source macroblock for
Decoding means for generating prediction source information by decoding the prediction source macroblock extracted by the second extraction means;
A program causing a macro block extracted by the extraction unit and a second distribution unit to distribute prediction source information to the client terminal by the generation unit . The computer-readable recording medium which recorded the program of Claim 9 .

Images